Communication in a fading channel (such as a high frequency channel) or in a noisy channel (such as the input-output interface of a disk drive) requires error correction encoding and decoding to recover data lost due to noise or fading. Encoding and decoding systems using, for example, Reed-Solomon codes, can correct twice as many erasures as they can errors for a given number of redundant symbols per codeword. Thus, error correction capacity is significantly enhanced by providing the decoder with the locations of erasures in a received codeword before the decoder begins decoding that codeword. The problem is how to predict where the erasures will be. This problem was solved using techniques which are a subject of U.S. Pat. No. 4,559,625 by Elwyn R. Berlekamp and Po Tong. The solution is to helically interleave a block of codewords together prior to transmission. Upon reception, and depending upon the position of a given symbol in the codeword, the receiver has already decoded a number of codewords containing symbols which were transmitted immediately preceding the given symbol of the present codeword. Therefore, the decoder knows whether or not the immediately preceding symbols were erroneous in the prior codewords. In one embodiment, the decoder simply inquires whether the symbol transmitted immediately before the current symbol of interest was identified as an error location when it was decoded. If so, the current symbol is identified as an erasure location to the decoder before the decoder begins decoding the present codeword.